FacePAD (Facebook Photo Album Downloader) allows you to download entire Facebook albums with a click of a button. It is a Firefox add-on that allows you to download your friends’ entire Facebook albums with a click of a button.
FacePAD makes it easy to grab all the pictures from any album you have access to. Whether you want to download your own pictures, pictures from the album of a friend, or from an event album etc, FacePAD makes it do-able from your right click context menu in facebook.
Download All Photos in a Facebook Album in One Click
To Install FacePAD Addon : Click Here
Step 2 : A window will pop-up asking you to choose a directory/folder where you would like the photos to be stored.
Step 3 : The photos will then be downloaded and renamed in sequential, ascending order as in the album.
Similarly to download photos from the group/event/page album, click on the photo tab. Right-click on any album link and click the “Download Album with FacePAD” option.
Here is a video tutorial by the creator of this plugin, Click here to watch it 
Note : There might be a hang time of a few seconds for large albums as it searches through the facebook album and then it begins downloading.
Source: www.snaphow.com